Are you then looting somebody every time you make a cash withdrawal?
Social Security, on the other hand, is a "pay as you go" program. When you contribute money into the Social Security trust fund, it is used to satisfy payments to current recipients. If it's still solvent and operating when you retire or become disabled, then you can expect to receive benefits similarly (though, technically, retirement/"old age" and disability benefits come from different funds).
Moreover, if the fund were to go insolvent — or Congress were to shut the program down — tomorrow, you would have no recourse. (Whereas with bank deposits, you have recourse at least up to the FDIC insured maximum.) If you renounce your US citizenship, or decide to fund your retirement yourself, you don't somehow magically get back the money you contributed, and you're still subject to payroll taxes in the latter case.
PS: congress is just as capable of shutting down the FDIC as the SSA
That's now how it works. The reason you get those annual pamphlets from Social Security Administration is to know exactly what you're entitled to. It's highly dependent on your rate and consistency of contributions.
> or decide to fund your retirement yourself, you don't somehow magically get back the money you contributed
Not sure what you're saying. When you reach proper age, you're entitled to Social Security payouts as long as you've contributed into the system the way that was intended. A lot of people fund their own retirements through 401(k), annuities or personal savings, that does not disqualify them from Social Security.
Either it's a trivial point that applies pretty broadly outside of SS, or you meant something more significant and I'm interested in knowing what that is.